Well flow apparatus and system



June 23, 1953 c. D. FLETCHER 'WELL. FLOW'APPARA'I'US AND SYSTEM Filed July 9, 1948 b n 4 3 a 8 7 0 AT W6 4 Z Z5 5 2 C Z ZQ N J E 4 NW j l 3a A S\\ c I a 14 3 0 p w w \\M .\\\U \A? vq\\ \\\-\W\. 5 M 5 6 O a 4 W 22 .A J m 5 a 0 J 2 5 o 4 w m VI 1 W 6 W W w M A w v U A U M Patented June 23, 1953 WELL FLOW APPARATUSAND SYSTEM Clarence D. Fletcher, Fort Worth, Tex., assignor to Merla .Tool Corporation, Dallas, Tex., a. corporation of Texas Application July 9, 1948, Serial No. 37,912

13 Claims. (01. 103-233) This invention relates to new and useful improvements in a well flow apparatus and system.

Various types of well flow apparatus are in general use for lifting or raising well fluids upwardly through a flow conductor or tubing by means of an auxiliary lifting fluid, such as gas or air which is introduced into the flow conductor or tubing from the annular space surrounding the tubing between said tubing and the outer well casing. One well known type of apparatus, normally referred to as a time-cycle intermitting system, employs a valve or valves connected in the flow conductor for controlling the admission of the lifting fluid or gas into said conductor-to raise the well fluids therein and said valve or valves are operated intermittently in accordance with particular well conditions. The control of the operation of the gas-admission valve or valves is accomplished by means of a time cycle device or controller at the surface which either opens said valves by a mechanical means or in those instances where the admission valves are pressure-actuated, functions to admit pressure into the annulus surrounding the how conductor to build up the pressure to a point capable of operating said valves.

The use of a time-cycle controller has certain disadvantages in that it actuates the lifting gasadmitting valve or valves at specific, predetermined time intervals without regard to the column of well fluid which may or may not be present in the flow conductor. Further, when a series of pressure actuated control valves are employed in conjunction with a time-controller, it has been necessary to construct or adjust the valves to operate at different operating pressures, that is, each valve operates at a lower pressure than the valve thereabove which places the lowest pressure operated valve at the bottom or lower end of the flow conductor, This is disadvantageous because of the range of gas pressure which is required at the surface in order to provide sufficient operating pressure in the lower end of the well bore.

It is, therefore, one object of the present invention to provide an improved flow apparatus or system, of the intermitting type, which employs a series of pressure operated valves for controlling the admission of a lifting gas into a flow conductor or tubing and which utilizes, in place of the usual time-cycle controller, a choke at the surface when the lifting gas is provided from the sub-surface formations or from a source having a fairly constant'pressure or which employs a choke together with a regulator device at the surface whenfan auxiliary lifting gas is used, whereby the system is simplified and is more posi-' gas-admitting valves are mounted; the use of said regulator making it possible to load the valves in such manner that all of said valves have the same closing pressure; with the opening pressure of said valves being controlled solely in accordance with the back pressure acting thereon from within the flow tubing which back pressure is a function of the well fluids within said tubing, the arrangement varying the operating range or spread of each valve in accordance with the par-,

ticular well fluid conditions at the level of that whereby said annulus is normally loaded with a predetermined pressure; opening of said valve being effected automatically when the back pressure on said valve which is caused by the fluid column rising in said flow conductor reaches a predetermined point, whereby the lifting gas is admitted from the annulus when a predetermined fluid column is present in the flow conductor;

closing of said valve resulting when the annulus pressure is reduced blow the predetermined closing pressure for which the valve is adjusted.

Still another object of the invention is to pro-- vide a well flow system, of the character described, wherein the regulator at the surface is set to Iopen to admit additional lifting gas into the annulus at a pressure which is above the pressure at which the gas-admitting valve in the flow conductor will close, whereby additional lifting gas is introduced into said annulus while gas fapparatus.

pressure controlled regulator l9. regulator may be any standard regulator'which 3 is still flowing into the flow conductor for lifting purposes; there being a restrictin means or choke associated with the regulator, so that the volume of gas being admitted into said annulus is less than the volume of gas flowing from said annulus through the gas-admitting valve and into the flow conductor, whereby even though additional gas is being introduced into the annulus, the annulus pressure may be reduced to the closing pressure of the valve to shut off fur- 1 ther admission of lifting gas into the conductor until the next subsequent operation of said valve, said regulator being set to automatically close when a predetermined pressure is attained in the annulus.

A further object of the invention is to provide an improved well flow apparatus including a valve constructed so that it has a fixed closing pressure, that is, said valve will close when a predetermined pressure is present in the annulus outside the flow conductor; the valve being exposed to the back pressure which is present in the flow conductor or tubing, whereby as this back pressure varies the pressure at which the valve opens varies so that actually the operating range or spread of said valve, that is, the range between closing and opening pressures is directly proportional to the back pressure on said valve.

The construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing, wherein an example of the invention is shown, and wherein:

Figure 1 is a view partly in section and partly in elevation of an improved well flow apparatus or system constructed in accordance with the 3 invention, and Figure 2 is a transverse, vertical, sectional view of one of the flow or gas-admitting valves of the In the drawings, the numeral l designates a well bore through which the usual well casing ll extends. The usual casing head I2 is mounted at the upper end of the casing at the surface and a well tubing or flow conductor l3 extends axially through the casing and has its upper end projecting outwardly through the casing head. The invention will be described as operating with an auxiliary lifting gas furnished from a suitable source and in such event, a

well packer M of any desired construction and which is shown schematically surrounds the tubing near its lower end, functioning to pack oil? the annulus A between the tubing and the casing. The well tubing or flow conductor has the usual inlet ports H3 in its extreme lower end below the packer, whereby the well fluids from the formation may enter and flow upwardly within the tubing or conductor I3.

A lifting fluid, which will be referred to herein as a lifting gas although it may be air or other fluid, is adapted to be conducted into the upper end of the annulus A through an inlet pipe [6 which is connected within an inlet opening I! provided in the casing head I2. A motor operated valve I8 is connected in the inlet line 16 and its opening and closing is controlled by a Although the may be purchased on the open market, it is preferable to employ a pressure control pilot unit which is exceptionally sensitive to controlled pressure and which is adapted to open and close the motor valve in respect to pressure condi tions within the annulus A.

The regulator is so arranged that when the pressure in the annulus falls below a predetermined pressure, the motor valve opens to admit additional pressure fluid; upon the attainment of a predetermined pressure within the annulus A, the regulator operates to close the valve l8 and shut off the further admission of pressure fluid into said annulus. In order to control the volume of flow of the pressure fluid into the annulus A, a suitable choke 20 is connected in the inlet line [6 and obviously, this choke will limit the volume of admitted pressure fluid when the motor valve I8 is open.

A plurality of flow valves of the intermitter type which are indicated VI, V2, V3 and V4 in Figure 1 of the drawings, are connected in the well tubing or flow conductor l3 at predetermined spaced levels or elevations. The construction of these valves is subject to some variation and said valves are arranged to control the admission of pressure fluid from the annulus A into the well tubing or flow conductor I3. It will be evident that when lifting gas from the annulus is admitted into the well tubing, said gas will function to lift the well fluids within said tubing to the surface. As above stated, the valves VI to V4 are of the intermitter type and are adapted to operate intermittently or at intervals to inject a slug of lifting gas into the liquid column.

One type of intermitter valve which has been found adaptable for use in this apparatus is illustrated in Figure 2 and as shown comprises an outer casing which is formed of an upper or pilot valve section B, an intermediate or power bellows section C and a lower or main valve section D. The sections B and C are connected by a coupling 2|, while the sections C and D are connected by a similar coupling 22. The pilot valve section B includes a pilot bellows 23 which has its upper end connected to the lower portion of a closure 24 which closes the upper end of said section. The lower end of the power bellows is connected to a pilot valve stem 25 having a pilot valve 26 secured to its lower end. A coil spring 21 surrounding the valve stem 25 has its lower end engaging the valve 26 with its upper end engaging an inwardly directed flange 28a which is formed at the lower end of a guide sleeve or tube 28 within which the pilot bellows 23 is disposed. The spring 2! constantly urges the valve into engagement with a valve seat 29. The valve seat is mounted within the upper end of an axial bore 30 provided in the coupling 2!. Inlet openings 3| are formed in the wall of the section B, whereby the lifting gas from the annulus may enter the interior of the section B and may, through the lower end of the bore and radial ports 28b in the wall of the sleeve 28 act upon the pilot bellows 23. The interior of the pilot belows contains a predetermined volume of liquid to protect the bellows against rupture under excessive pressure.

The pressure of the spring 2'. controls the pressure at which the pilot valve 26 will open liecause obviously, the lifting gas present in annulus A enters the interior of the section B and acts upon the cross-sectional area of the pilot-bellows. This lifting fluid pressure must build up sufliciently to overcome the force of the spring to compress the same before the pilot is opened. As soon as the; pilot valve vllipens the additional area of said pilot valve,- which is normally within the seat 23, is immediately exposed to the pressure and the valve is moved to full open position. As the pressure in the annulus A is reduced to a point insufiicient to overcome the downward force of the spring 2?, said spring overcomes the action of the pressure on the crosssectional area of the pilot bellows 23 and the pilot valve is closed. It will be obvious that when the pilot valve is in a closed or seated position. the underside of said valve is withinthe bore 39 and is not exposed to the annulus pressure but where the valve is unseated, this underside area is acted upon by said annulus pressure. Therefore, the opening pressure, that is, the pressure necessary to open the pilot, is greater than the pressure at which the valve closes. This difference in opening and closing pressures will-be referred to herein as the range or spreadoi' the valve units VI to V4.

Within the intermediatesection 7C is a power bellows 32 which has its lower end secured to an extension 22a formed on the coupling 22. The upper end of the power bellows is secured to an enlarged cap 33 which is formed integral with an elongate operating stem The lower portion or the operating stem extends through the axial bore 35 of the coupling 22 and this portion of the stem is hexagonal or angular whereby by-pass passages 36 are formed between the stem and the bore. A radial bleed port 3'! extends through the wall of the bellows 32 so that a flow from the bore 35 to the interiorof the intermediate section C may occur, such communication between the interior and exterior of the bellows being at a controlled rate in accordance with the size of the port.

The lower end of the operating stem extends into the lower main valve section D and is adapted to engage an axial shanl: of a main valve member 39. The main valve member is adapted to engage a valve seat 40 formed within the section I) when in its upper or raised position. A radial port ll extending from the bore 42 of the section D communicates with an inlet port 42-3 formed in the well tubing l3, whereby communication is established between the bore of the lower section D and the interior of the well tubing. An inlet screen 44 or perforated strainer tube is connected to the lower end of the section D and establishes communication between the annulus A and the lower portion of the main valve section D.

It will be evident that with a pressure within the annulus A, such pressure will act against the lower end of the main valve 35 and will maintain the same seated. The pressure in. the annulus may also act through the ports 3! in the pilot section B and upon the pilot bellows but presuming that such pressure is insuilicient to open the pilot valve, the main valve as will remain closed. Any back pressure on the valve, that is. any pressure from within the flow conductor l3 will act through the port Ill and as and within the lower section D. This pressure may also flow upwardly past the angular portion of the operating stem 34 and into the interior of thepower bellows. Through the bleed port 3'. in the bellows, this pressure may equalize exteriorly of the bellows within the bore C of the intermediate section C and since the section C is in communication with the bore 39 of the coupling 2|, the back pressure from the well tubing may act against the cross-sectional area of the pilot valve 26 which is exposed within the valve seat 29. If there is no back pressure within the flow tubing due to the absence of well fluids therein, there will be no pressure acting against the underside of the pilot valve 26 and under such a condition, the pilot valve will remain closed until the pressure within the annulus A is sufficient to overcome the tension or force of the coil spring 21.

For purposes of this description and merely by way of example, it will be presumed that under atmospheric conditions, the closing pressure of the pilot valve 26 is 400 pounds while the opening pressure will be presumed to be 450 pounds. Under this assumption, when the annulus pressure reaches 460 pounds the pilot valve 26 opens and the pressure of the lifting fluid within the annulus acts on the exterior of the power bellows 32 and functions to compress or collapse the bellows, whereby the operating stem 34 is moved downwardly. Because the effective cross-sectional area of the bellows is greater than the effective cross-sectional area of the main valve 39, it will be evident that the main valve will be moved downwardly off of its seat, whereby the lifting fluid pressure may flow past the seat 40 and through ports 4! and 43 into the flow tubing. Just as soon as the annulus pressure falls below the assumed closing pressure of 400 pounds, the pilot valve 26 is closed by the spring 21. The pressure exteriorly of the power bellows 32 is bled off through the bleed port 33 thereby permitting the difierential across the main valve 39 to move said valve to its closed position.

It will be evident that any back pressure pres-' out within the tubing will act against that crosssectional area of the pilot valve 25 which is exposed within the valve seat 29 and this back pressure will be added to the lifting fluid pressure 7 which is tending to open the pilot valve. Therefore, with a back pressure present within the flow stream, the opening pressure of the valve is altered and as a specific example it has been found that with a presumed opening pressure of 460 pounds at atmosphere, a back pressure of pounds acting on the pilot will cause the valve to open when the annulus pressure reaches 445 pounds. A back pressure of 200 pounds acting against the pilot will reduce the opening pressure to 432 pounds while a back pressure of 309 pounds will further reduce the opening pressure to 420 pounds. This reduction in the opening pressure is, of course, based on a particular ratio between the area of the pilot valve seat 23 with respect to the efiective cross-sectional area of the pilot bellows for obviously byvarying the ratio between the area of the valve seat 29,'which is the area exposed to back pressure, with respect to the cross-sectional area of the pilot bellows acted upon by the annulus pressure, it is' possible to control the pressure which must be attained within the annulus before the pilot valve opens. It is noted that the back pressure affects only the opening pressure because after the valve opens the underside thereof is exposed to the annulus pressure; however, in all cases with the valves constructed identically, the closing pres sure will remain the same which as presumed, will be 400 pounds. Therefore, actually the operating range 'or spread of the valve, that is, the spread between opening and closing pressures varies proportionately to the back pressure acting on the valve. The particular operating range or spread may, as above pointed out, be controlled accurately by varying the ratio between 7 the diameter of the valve seat and the effective cross-sectional area of the pilot bellows.

In the operation of the apparatus, the valves VI to V4 will be assumed to have the presumed 400 pounds closing pressure. All of said valves may be constructed with their pilot bellows bearing the same ratio to the pilot valve seat. Under such a situation, the operating range between opening and closing pressures on all valves would be alike under similar back pressure conditions. However, if desired, certain of the valves may have different ratios between the pilot valve seat and the pilot bellows in which event the operating range or spread between opening and closing pressures of each valve under a given back pres= sure condition would be different than the remaining valves.

At the start of the/operation it is presumed that all valves will have some back pressure thereon and lifting fluid is admitted into the annulus through the motor valve is and choke 20 for the purpose of unloading the tubing. The lower valves V3 and V4 will have sufiicient back pressure thereon due to the liquid load in the tubing whereby these valves remain open during the unloading operation. As soon as the pressure in the annulus builds up to a point sufficient to open the uppermost valve vi, a charge of gas is admitted into the flow tubing and the fluid above this level is lifted to the surface so that the back pressure on this particular valve is substantially nil. Under the presumed conditions. the opening pressure at atmosphere of the valve is 460 pounds while under a 100 pound back pressure the opening pressure is 445 pounds. Therefore, assuming a 100 pound back pressure on valve V when the annulus pressure reached 445 pounds the valve opened and as soon as the fluid was lifted to reduce the back pressure, the opening pressure of this valve immediately raised to 460 pounds. Thus, the upper valve becomes inactive and since the next valve below has some back pressure upon it its opening pressure is less than the opening pressure of the uppermost valve. Thus, the valves are operated successively until the working level of the installation is reached. This working level would be at the particular valve where the flowing bottom hole pressure of the well would feed past the valve at a pressure equal to or slightl less than the operating pressure of that valve. In other words, this working level may be found at valve V3 or it may be at valve V4. The remaining valves in the tubing would remain inactive until such time as the back pressure conditions within the tubing changed so as to bring those valves in operation in accordance with the annulus pressure. Any valve or valves below the working level would, of course, remain open but will be inactive so far as con.- trolling the admission of the lifting gas.

The regulator and the choke 20 are important in the operation of the system because it is necessary to control the incoming pressure fluid during the operation of the valve which is functioning at the working level. It will be assumed that the working level is at valve V3 which is operated on a 32 pound spread, that is, the valve will open at 432 pounds and will close at 400 pounds. Under such a condition it is desirable to build the annulus pressure to 432 pounds and the regulator I 9 is provided for this purpose. At the time that the annulus is charged to 432 pounds, the well fluids within the tubing and acting on the valve V3 as back pressure are not sufficient to produce a 200 pound back pressure which is the amount necessary to cause the valve to open. However, as the well fluids continue to build up and finally exert a 200 pound back pressure on said valve, the 432 pounds charged pressure in the annulus becomes sufficient to open the pilot 26 and then open the main valve 39, whereby a charge of lifting gas is introduced into the flow tubing. As the gas is admitted to the tubing to lift the well fluids therein, the annulus pressure is obviously reduced and continues to reduce toward the 400 pounds pressure at which the valve will close. The regulator I9 is so adjusted at the surface that as the annulus pressure decreases to a point close to the 400 pounds closing pressure, as for example at 405 pounds, said regulator functions to open the motor valve I 8 and admit additional lifting fluid into the annulus A. The choke is so arranged that its capacity is less than the capacity through the valve V3, with the result that the lifting gas is admitted into the annulus in a volume less than that passing through the valve. Therefore, even though pressure fluid is being admitted into the annulus through the choke, it is not admitted in sufficient volume to pr vent a further reduction in the annulus to 400 pounds closing pressure of the valve. As soon as the closing pressure is reached in the annulus, the valve V3 closes but the regulator continues to hold the inlet valve l3 open until the annulus pressure has again built up to the 432 pounds pressure which will be required to open valve V3 when the fluid column has built up to the required 200 pounds back pressure.

From the foregoing it will be evident that a well flow apparatus is provided which will operate intermittently and automatically without any time controller mechanism such as is usually employed in the intermitting type of systems. It is possible to obtain the maximum well production and to maintain the lowest possible gasoil ratio because obviously the valve does not open until suflicient fluid accumulates in the flow tubing. The weight of the column of gas from the surface down to the operating valve. subtracted from the closing pressure of the valve provides the surface gauge reading, whereby the location of the operating valve may be determined. By computing the displacement of the gas in the casing annulus according to the opening and closing pressures of the valve and by computing the amount of fluid in the tubing according to the back pressure and fluid gradient. it is possible to ascertain the gas-oil ratio. The use of the regulator and choke at the surface provides a much simpler arrangement than a time-controlled device. It is obvious that any operating range or spread may be given to the valve since it is only necessary to vary the ratio of the pilot valve seat to the power bellows to obtain different operating ranges or spreads.

The bleed port 31 which is provided for bleeding the interior of the power bellows enters into the operation of the device in that it controls the amount of pressure which is obtainable in the power bellows during operation. By changing the size of this bleed port 31 with respect to the size of the pilot seat, it is possible to control or vary the amount of pressure which may be obtained in the power bellows. Thus, it will be seen that the ratio between the pilot seat and the effective cross-sectional area of the pilot bellows is the governing factor in controlling the operating range or spread which the valve will have under particular back pressure conditions.

to omit the regulator 9 The ratio between the pilot seat and the power bellows bleed port 31 enters into efficient valve operation, that is, in efiicient opening of the main valve 31, following unseating of the pilot valve.

As above pointed out, the particular s stem permits the use of an ordinary regulator for automatic operation in place .of the uncertain time-controlling device at the surface. It also permits all of the valves to be initially arranged so as to have the same closing pressure. Although a particular type of pilot controlled intermitter valve is illustrated, it is noted that any intermitting type of flow device wherein the back pressure within the tubing functions to vary the opening pressure of the valve, maybe employed.

The improved apparatus has been illustrated and described as operating in a -so -called closed system wherein the well packer 1.4 seals off the lower end of the annulus A from the sub-surface formations. However, in some cases and under proper conditions, the lifting gas required for purposes of lifting the fluid within the flow conductor may "be furnished from the sub-surface formations. choke 2B would not be necessary, the upper end of the annulus being shut off by a suitable valve which would remain closed. The valves V1 to V4 would be set at a pressure slightly lower than the pressure that the well .was .capable of building up in-the annulus. When this annulus pressure builds up to the .opening pressure ,of the valve, the back pressure in the flow conductor acting on the :valve would cause the same to open. The flow through the valve would be f greater in volumethan that entering the annulus from the formations and this would allow the annulus pressure to bleed back to the closing pressure ofthe valve exactly in the manner above described with respect to an auxiliary lifting gas. The valve wouldobviously stay closed until the casing pressurezbuilt back up.

It would also be possible in certain instances ID from the system, ,as shown in the drawings. -Where the auxiliary lifting-gas is providing from a casing-head gasolineplant or from a gas system maintaining .a

fairly constant gas pressure, the regulatorisnot necessary. 'In this case the valves would'be .set towork-fromthis substantially constant pressure and only the choke would be'employedto restrict the volume of incoming "gas-when one of the valves is opened to lift" well fluids through the conductqnas above described. The foregoing description of the invention-is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within thescope of the appended claims, without departing from the spirit of the invention. What I claim and desire to secure=by Letters 'Patent is:

,the casing an inletvalve in said line for controlling the admission of lifting gas into the annulus, whereby said annulus may be charged to a predetermined pressurea regulator actuated in accordance with the annulus pressureforcontrolling the operation of theinlet valve iand a.

In such event the regulator 19 and,

pre sure-actuated ra connected n e wel tubin and h vi rede erm ne fix 1 i c pressure controll d s e in wa ens? wi h the res ure n theannulus W t e hl pressure var ab e and controlled by ha pre sur within t e 119W c uctor s di a i said valve a d prsssu ea mai d v v 'l trolling. theadmission h lift n gas m" t annulus into the welltu ing to iii t e w flui marginv u ,7 1 2. ,A well flow apparatus as set forth in claim 1, together with a choke m ans onne ted the inlet line for restricting t lum o gas admitted to the annulus to a volume less than volume .0; thi g a whi n w th the ope pressure-a tuated all wher b t villinulus pre ure may bleed d w to hec o i is p essure of the hire sureaci a c v a ve fo the annulus is rechar ed to the predetermined hi her pressurex 3. A .well flow apparatu includin a w casing extending within a well bore, a well tubing extending axially through the well casing and having a .well fluid inlet in its lower, end, means for packing oil the annulus between said tubing and casing above the well fluid inlet, a lifting gas inlet line connected .wit the up er n O th casing, an nlet valve in said i e for co rollin vthe admission ,of lifting gas into the annulus, whereby said annulus may be charged to a p edetermined pressure. a reg lato a tuat d in accordance .with the .-.a.. nulus pressure for controilingithe operation ,of the inlet valve, aphirality of pressure-actuated valves connected in the well tubing at various spaced levels or eleva- .tions,,a1l of saidyalves being set to the same closing pressure with the opening pressure of each valve beingcontrolledby theback pressure within the flow conductor at the particular valve level. whereby when the bac pres i011 a particular valve reaches a predetermined point said .valve opens .to admit lifting gas from the annulus into .the .yv-ell tubing to lift the well .fluids therein, openingof one of the pressureactuated ,valves reducing the pressure in the J annulus, whereby the regulator opens the inlet .valve Lto admit additional lifting gas into the annulus, and icholge rn eans in the inlet line for admittingtheadditional lifting gas in avoluine less than the volume fiowing through the open .valve .wherebythe. annulus p essur a b firs reduced .to .the fixed closing pressure of the pressure-actuated ,valve ,before said annulus is .remharged to thepredeterminedhigher pressure.

.4. A. systemic! flowing wellsincluding, a lit;- uid conductor extendingjaxially through a well bore. and having a liguid inletinits lower end, -means for introducing a lifting gas into the annulus .around ,the conductor, a pressure-actuated .valve .mounted in ,the vflow conductcu ,for controlling admission of.lifting. gas intov the conductor, said valve having operating means ,responsive whenthe valve is open tdannuluspressure and preset to close said valve when .the "lifting gas pressure falls to a predetermined point, said operating means being responsive when r the valve is closed to the combined pressure of the well liquid .withinthe conductor and the pressure in" the .annulus .and being .set to operate" andopen. the .valve whensaid combined gp'ressures attaina predetermined. pressure, and a --reg-ulator actuated .in accordance vwithflthe annulus pressure 1 for controlling said annulus .-.pressure. A.-we11.-.-nuw..apnara12us. ncludinaa fiow. .on-

controlling the admission of lifting gas from the annulus into the conductor, operating means including a pilot valve which controls application 'of pressure to the main valve, said pilot valve 'being movable to one position to shut off pressure from the main valve to thereby close said main valve and being movable to a second position to admit pressure against the main valve member to thereby open said main valve member, the operating means being exposed to the pressure in the annulus and the back pressure in the flow conductor when in its first position whereby movement of said means and its pilot valve from the first position to open the main valve member is effected by the combined pressures in the annulus and flow conductor, said operating means being exposed only to the annulus pressure when in its second position, whereby a predetermined annulus pressure moves the pilot valve from its second position t its first position to effect a closing of the main valve member, and a regulating device in the lifting gas conducting means and actuated in accordance with the lifting gas pressure within the annulus, whereby when the pressure-actuated valve opens to admit lifting fluid into the flow conductor to thereby lower the annulus pressure, said regulating device is actuated to admit additional lifting gas into the annulus.

6. A well flow apparatus including, a flow conductor extending axially through the well bore and having a well fluid inlet at its lower end, means for packing off the annulus between said conductor and the well bore above the well fluid inlet of said conductor, means at the well surface for conducting a lifting gas into the annulus around the flow conductor, whereby said annulus may be charged with a predetermined lifting gas pressure, a pressure-actuated valve including a main valve member and mounted in communication with the flow conductor for controlling the admission of lifting gas from the annulus into the conductor, operating means including a pilot valve which controls application of pressure to the main valve, said pilot valve being movable to one position to shut off pressure from the main valve to thereby close said main valve and being movable to a second position to admit pressure against the main valve member to thereby open said valve member, the operating means being exposed to the pressure in the annulus and the back pressure in the flow conductor when in its first position whereby movement of said means and its pilot valve from the first position to open the main valve member is effected by the combined pressures in the annulus and flow conductor, said operating means being exposed only to the annulus pressure when in its second position, whereby a predetermined annulus pressure moves the pilot valve from its second position to its first position to effect a closing of the main valve member, a regulating device in the lifting gas conducting means and actuated in accordance with the lifting gas pressure within the annulus, whereby when the pressure-actuated valve opens to admit lifting fluid into the flow conductor to thereby lower the annulus pressure, said regulating device is actuated to admit additional lifting gas into the annulus, and means also connected in the conducting means for controlling the rate at which the lifting gas is admitted to the annulus.

7. A well flow apparatus including, a flow conductor extending axially through the well bore and having a well fluid inlet at its lower end, means for packing off the annulus between said conductor and the well bore above the well fluid inlet of said conductor, means at the well surface for conducting a lifting gas into the annulus around the flow conductor, whereby said annulus may be charged with a predetermined lifting gas pressure, a pressure-actuated valve including a main valve member and mounted in communication with the flow conductor for controlling the admission of lifting gas from the annulus into the conductor, operating means including a pilot valve which controls application of pressure to the main valve, said pilot valve being movable to one position to shut oif pressure from the main valve to thereby close said main valve and being movable to a second position to admit pressure against the main valve member to thereby open-said valve member, the operating means being exposed to the pressure in the annulus and the back pressure in the flow conductor when in its first position whereby movement of said means and its pilot valve from the first position to open the main valve member is effected by the combined pressures in the annulus and fiow conductor, said operating means being exposed only to the aimulus pressure when in its second position, whereby a predetermined annulus pressure moves the pilot valve from its second position to its first position to effect a closing of the main valve member, a, regulating device in the lifting gas conducting means and actuated in accordance with the lifting gas pressure within the annulus, whereby when the pressure-actuated valve opens to admit lifting fluid into the flow conductor to thereby lower the annulus pressure, said regulating device is actuated to admit additional lifting gas into the annulus, and a choke connected in the conducting means for controlling the volume of lifting gas admitted to the annulus, said choke admitting the lifting gas to the annulus at a rate which is less than the rate at which lifting gas flows through the pressure-actuated valve into the flow conductor.

8. A well fiow apparatus including, a flow conductor extending axially through the well bore and having a well fluid inlet at its lower end. means for packing on the annulus between said conductor and the well bore above the well fluid inlet of said conductor, means at the well surface for conducting a lifting into the annulus around the flow conductor, whereby said annulus may be charged with a predetermined lifting gas pressure, and a plurality of pressure-actuated main valves connected in the flow conductor at various spaced levels or elevations, an operating means for each main valve and including a pilot valve for admitting or shutting off pressure to said main valve, each operating means and its D lot valve being actuated to shut off pressure to the main valve when a predetermined pressure is attained in the annulus, said operating means and its valve being actuated to admit pressure to the main valve when a predetermined annulus pressure added to a predetermined pressure within the ilow conductor is attained, the open ating means of all of said main valves being set for actuation to close the main valve upon the attainment of the same pressure within the annulus, each main valve when opened admitting lifting gas from the annulus into the flow conclusters to lift the well fluids therein.

9. A well iiow apparatus as set forth in claim 8, together with a regulator mounted in the lifting gas conducting means and actuated in accordance with the lifting gas pressure within the annulus, whereby a reduction in annulus pressure due to opening of any of the pressure-actuated valves to admit lifting fluid into the flow conductor actuates said regulator to admit additional lifting gas into the annulus.

18. A well flow apparatus as set forth in claim 8, together with a regulator mounted in the lifting gas conducting means and actuated in accordance with the lifting gas ressure within the annulus, whereby a reduction in annulus pressure due to opening of any of the pressure-aotuated valves to admit lifting f lid into the flow conductor actuates said regulator to admit additional lifting gas into the annulus, and means for admitting the additional lifting into the annulus at a rate which is less than the rate of escape of lifting gas through the open pressureactuated valve, whereby said annulus pressure may be reduced to the closing pressure of said valve before said annulus pressure is again built up to the predetermined pressure to which annulus is normally charged.

11. A. "ell flow apparatus including, a flow conductor extending axially through the well bore and having a well fluid inlet at its lower end, means for packing off the annulus between said conductor and the well bore above the well fluid inlet of said conductor, means at the well surface for conducting a lifting gas into the annulus around the flow conductor, whereby said annulus may be charged with a predetermined lifting gas pressure, a pressure-actuated valve including a main valve member and mounted in communication with the flow conductor for controlling the admission of lifting gas from the annulus into the conductor, operating means in-- eluding a pilot valve which controls application of pressure to the main valve, said pilot valve being movable to one position to shut off pressure from the main valve to thereby close said main valve and being movable to a second position to admit pressure against the main Valve member to thereby open said main valve member, the operating means being exposed to the pressure in the annulus and the back pressure in the flow conductor when in its first position whereby movement of said means and its pilot valve from the first position to open the main valve member is eiiected by the combined pressures in the annulus and flow conductor, said operating means being exposed only to the annulus pressure when in its second position, Wherebya predetermined annulus pressure moves the pilot valve from its second position to its first position to effect a closing of the main valve member, and means connected in the conducting means for controling the rate at which the lifting gas is admitting to the annulus.

A well flow apparatus as set forth in claim 11, wherein the rate controlling means is a choke which admits the lifting gas into the annulus at a rate which is less than the rate at which lifting gas flows through the pressure-actuated valve into the flow conductor.

13. A well how apparatus including, a Well casing extending within a well bore, a well tubing extending axially through the Well casing and having a well fluid inl t in its lower end, means for packing off the annulus between said tubing and easing above the Well fluid inlet, a lifting gas inlet line connected with the upper end of the casing, an inlet valve in said line for controlling the admission of lifting gas into the annulus, whereby said annulus may be charged to a predetermined pressure, a control means for controlling the operation of the inlet valve, a plurality of pressure-actuated valves connected in the wall tuning at various spaced levels or ele-v vations, all of said valves being set to the same closing pressure with the opening pressure of valve being controlled by the back pressure within the :El w conductor at the particular valve level, whereby when the back pressure on any particular valve reaches'a predetermined point said valve opens to admit lifting gas from the annulus into the well tubing to lift the well fluids therein, opening of one of the pressure-actuated valves reducing the pressure in the annulus, and choke means in the inlet line for controlling the admission of additional lifting gas in a volume less than the volume flowing through the open valve whereby the annulus pressure may be first reduced to the fixed closing pressure of the pressure-actuated valve before said annulus is recharged to the predetermined higher pressure.

CLARENCE D; FLETCHER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name, Date 1,847,295 Dunn Mar. 1, 1932 2,142,484 Jennings Jan. 3, 1939 2,204,834 Temple June 18, 1940 2,306,828 Mowrey Dec. 29, 1942 2,339,487 King Jan. 18, 19 

